Stop Sexual Assault and Harassment in Transportation Act This bill establishes formal sexual assault and harassment policies for the transportation industry. Among other things, the bill requires certain passenger transportation carriers, including passenger airlines and vessels, buses, commuter and intercity passenger railroads, and transportation network companies (e.g., Uber or Lyft) to establish formal policies, training, and reporting structures regarding sexual assault and harassment; sets forth civil penalties for individuals who physically assault or sexually assault or threaten to assault transportation personnel; directs the Department of Transportation (DOT) to collect information on the number of sexual assault and harassment incidents reported by the carriers and make such information publicly available; expands the reporting process for individuals involved in transportation sexual assault or harassment incidents by allowing such individuals to report allegations to law enforcement in a manner that protects their privacy and confidentiality; assesses the accuracy of the reporting of transportation sexual assault or harassment incidents by the carriers; and requires DOT to develop and publish a definition of sexual harassment.